High Throughput plasma treatment system

ABSTRACT

A plasma treatment system ( 10 ) is provided having an automated, in-line processing ability. The preferred embodiment is directed toward plasma treatment of PC boards ( 28 ) but is generally applicable to any substrate susceptible of plasma reaction. The plasma treatment system ( 10 ) has the primary components of a reaction chamber ( 14 ) and chamber base ( 16 ), a chamber lifting assembly ( 18 ), a conveyor input assembly ( 12 ), a push mechanism ( 20 ) and associated linear drive assembly ( 22 ), an output assembly ( 24 ), an electronic control system ( 26 ), and a vacuum and plasma generating system ( 27 ). Each of the conveyor input assembly ( 22 ), reaction chamber ( 14 ), and output assembly ( 24 ) include pairs of guide rails ( 34, 52,  and  106 , respectively) which are capable of being juxtaposably aligned relative to one another and upon which the PC boards ( 28 ) may guideably and sideably travel. The push mechanism  20  effectuates both movement and positioning of the PC boards ( 28 ) along the guide rails ( 34, 52,  and  106 ). To allow placement of the PC boards ( 28 ) within the reaction chamber ( 14 ) and upon the chamber guide rails ( 52 ), the reaction chamber ( 14 ) is capable of vertical movement via the chamber lifting assembly ( 18 ), the reaction chamber ( 14 ) being open-bottomed and vacuum-tightly fittable upon the chamber base ( 16 ). Plasma treatment is initiated using conventional plasma generating elements. The push mechanism ( 20 ) and guide rail ( 34, 52 , and  106 ) arrangement provide that multiple PC boards may be properly positioned for simultaneous processing in an in-line fashion. Applied DC biasing ( 502 ) is used to increase etch rates and plasma flow directionality. An alternative embodiment ( 410 ) incorporates a multi-level guide rail arrangement together with vertically raiseable input and output carriers ( 110  and  122 ) to provide that two or more levels of PC boards ( 28 ) may be simultaneously treated by plasma reaction. A third embodiment includes supplies for applying Radio Frequency (RF) power ( 504 ) and DC bias power ( 502 ) to the gas plasma. By using vertical electrodes ( 598 ), the plasma can be made to flow horizontally between the layers of a multilevel array or magazine ( 620 ) that holds parts that are to be treated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S.application Ser. No. 08/601,687, which was filed on Feb. 15, 1996 and isa continuation-in-part of application Ser. No. 08/567,797, filed Dec. 5,1995, now U.S. Pat. No. 5,766,404, which is a continuation-in-part ofapplication Ser. No. 08/350,320, filed Dec. 5, 1994.

TECHNICAL FIELD

The present invention relates generally to apparatus for plasmatreatment, and more particularly to a plasma treatment system thatoffers an improved automated processing capability.

BACKGROUND ART

Gas plasma treatment of a variety of substrates, particularly those inthe electronics field, is a well-established and proven process thatincreases surface activation (wettability), improves die attach,increases the reliability and strength of wire bonds, and providesbetter adhesion for encapsulation. Plasma systems have been in use forover 25 years for such applications and offer significant advantagesover liquid chemical treatment methods and other dry methods such asozone.

Disclosed in U.S. Pat. No. 4,208,159, issued to Uehara et al. on Jun.17, 1980, is an apparatus that performs, in an automated assembly linemanner, the plasma treatment of individual electronic parts, namely,semiconductor wafers. Prior to the invention of Uehara, plasma treatmentof electronic parts was performed in batch-wise fashion. As Ueharadescribes, such simultaneous plasma treatment of a large number of partsgenerally does not result in an even reaction (i.e., etching orcleaning) at the surface of a substrate. Batch-wise treatment alsoreduces productivity by interrupting the flow of processing and assemblyof parts.

Uehara provides for a reaction chamber having an open bottom portion anda wafer “table” that moves vertically up and down to be vacuum-sealablewith the opening of the reaction chamber. The apparatus furlier includesan in-take carrier means for carrying a wafer to a position adjacent thewafer table, and an in-take pick-up means for picking up the wafer fromthe in-take carrier means and placing the wafer onto the wafer table.Disclosed in the patent are two combinations of such in-take carrier andpick-up means, one of which employs two revolving arms, each having asuction type pick-up, the other of which employs two linear travelingarms, each having a suction pick-up as well. After the single wafer hasbeen placed on the wafer table, the wafer table is raised to sealagainst the reaction chamber and the plasma process is initiated.Out-take means identical to the in-take carrier and pick-up means areused for removal of the treated wafer from the wafer table after thewafer table has been disengaged and lowered from the reaction chamberopening.

The invention of Uehara offers substantial advantages in that it makespossible the in-line, hands-off plasma processing of individual parts(wafers). However, both of the embodiments disclosed are much morelimiting in their scope of operation than is desirable. The inventiondoes not allow, when it is desired, for the plasma treatment of morethan one part at a time. It was noted previously that individualprocessing of parts is advantageous with respect to the evenness of theplasma reaction that may be obtained. However, it is also the case thata sufficiently uniform reaction may be obtained, depending on the natureof the parts (and upon appropriate spacing therebetween), where morethan one part at a time is treated. Uehara does not address this issue.In addition, pick-up mechanisms of the type shown in Uehara, which asnoted is in the form of a suction device, are known to be not entirelyfree from droppage and breakage of parts due to temporary loss orirregularity of vacuum pressure.

Shown in U.S. Pat. No. 4,318,767, issued to Hijikata et al. on Mar. 9,1982, is another automatic in-line plasma system for treatment ofsemiconductor wafers. Hijikata employs a non-movable reaction chamberwith a vertically movable wafer table contained therein. Shutter-likeslits, which are vacuum-sealable and which are present at opposing endsof the reaction chamber, provide entry and exit portals for the wafers.The wafers are introduced into the reaction chamber with a pair ofslidable parallel arms spaceably distanced so as to support a wafertherebetween. In the process sequence, a single wafer is loaded onto theends of the arms via a conveyor belt apparatus. The arms then slideforward to extend into the reaction chamber through the entry portalsuch that the wafer is positioned over the wafer table. The wafer tablemoves upward to a height just above the arms, lifting the wafer off ofthe arms in the process. After the arms have been retracted, the entryslit is sealed, the chamber evacuated, and the plasma process initiatedto treat the wafer lying on the table. The wafer is removed by extensionthrough the exit portal of a pair of arms identical to the onespreviously employed followed by a lowering of the wafer table, whichcauses the treated wafer to rest upon the arms. Retraction of the armsthen removes the wafer from the chamber.

Hijikata eliminates the precarious suction pick-up arrangement ofUehara, but again fails to offer an option for treating more than onepart at a time in an in-line fashion. Nor is the invention of Hijikataamenable to such, since even were more than one part crudely loaded ontothe ends of the sliding arms of the apparatus, no mechanism is availablefor properly spacing the parts upon the wafer table, such spacing beingcritical when more than one part is subjected to plasma treatment.

U.S. Pat. No. 4,889,609 to Cannella discloses an automated dry etchingsystem which is titled “Continuous” but utilizes input and output beltswhich are enclosed in pressurized chambers which are maintained at apreselected partial vacuum. The enclosed nature of these chambersnecessarily limit the number of parts that can be treated before thechambers have to be opened for loading a new batch to be processed.Additionally, the configuration of the input gate allows a very limitednumber of parts to be treated at once, and consequentially, thethroughput of this system can be expected to be likewise limited.

U.S. Pat. No. 4,252,595 to Yamamoto et al. illustrates a plasma etchingapparatus which includes a rotatable disk in the etching chamber, oralternately, a conveyer assembly, which is also included within theplasma chamber. Both of these variations can be expected to haveproblems related to the use of moving parts within the plasma chamber.Moving parts typically require lubricants, which can, over time,contaminate the etching chamber and the treated parts. Especially innear vacuum conditions, out-gasing of lubricants can be expected, andeffects of even minute amounts of contaminants can be cumulative overtime. Additionally, when moving parts are exposed to conditions such asin a plasma etching chamber, these parts are susceptible to corrosion.Moving parts which operate on fine tolerances can be expected to requirefrequent replacement when exposed to such harsh operating conditions.

U.S. Pat. No. 5,587,205 to Saito et al. also shows a plasma processingmethod including an electrode stage on a liffing mechanism. These movingparts can be expected to experience the same difficulties ofcontamination and corrosion discussed above. Additionally, thethroughput of the system would appear to be very limited.

U.S. Pat. No. 4,405,435 to Tateishi et al. discloses a plasma treatmentapparatus, but there is an elevator in the etching chamber, thusintroducing moving parts. Once again, these moving parts can be expectedto experience the same difficulties of contamination and corrosiondiscussed above.

Because of the limitations associated with most presently availableplasma treatment systems, a substantial need still exists for such asystem as offers improved processing capability while also providing forthe simultaneous treatment of a plurality of parts.

DISCLOSURE OF THE INVENTION

Accordingly, it is an object of the present invention to provide aplasma treatment system that provides an automated, processingcapability of electronic and other parts.

It is another object of the invention to provide a plasma treatmentsystem capable of treating a plurality of parts at once.

It is a further object to provide a plasma treatment system thatprovides precise spacing for the treatment of a plurality of parts.

It is yet another object to provide a plasma treatment system thatutilizes guide rails together with a distinct push mechanism forconveyance of the parts to be treated.

It is yet a further object to provide a plasma treatment system thatemploys infrared sensing devices to aid in the detection and positioningof the parts to be treated.

It is still another object to provide a plasma treatment system whereinno moving parts of the system are present within the reaction chamberduring the treatment process.

It is a still further object to provide a plasma treatment systemwhereby parts may be treated on multiple levels within the reactionchamber.

It is a yet another object of the present invention to provide a DC biasto the electrodes in order to promote better penetration of plasmabetween parts.

It is still another object of the present invention to increaseionization rates, and increase the energy of the ions and electrons tothus increase etch rates and decrease processing time.

It is a still further object of the present invention to provide moredirectional etching, resulting in more anisotropic etching, by using aDC bias.

It is an additional object of the present invention to provide a plasmatreatment system which utilizes vertically oriented electrodes toprovide better uniformity of treatment of parts.

Briefly, the preferred embodiment of the present invention is a plasmatreatment system having an automated processing ability. The preferredembodiment is directed toward plasma treatment of PC boards but isgenerally applicable to any substrate susceptible of plasma reaction.For the purposes of discussion, the typical object substrate is referredto as a PC board, although it is recognized that it could well be awafer or other object. The plasma treatment system has the prinarycomponents of a reaction chamber and chamber base, a chamber liftingassembly, a conveyor input assembly, a push mechanism and associatedlinear drive assembly, an output assembly, an electronic control system,and vacuum and plasma generating systems.

The conveyor input assembly includes a conveyor which rides upon aconveyor position actuator. A PC board is loaded onto the conveyor from,for example, a preceding belt-type conveyor in an overall assembly lineprocess. The reaction chamber is lifted vertically via the chamberlifting assembly, and the conveyor is moved by the conveyor positionactuator to be in aligned juxtaposition with the load end of a pair ofchamber guide rails which are present within the perimeter of thechamber base and which are further supported atop a reaction-inducingelectrode. The push mechanism moves the PC board from the conveyor andonto the chamber guide rails. The conveyor is then moved back to thestarting position so that another PC board may be conveyed and carriedby the conveyor. The second PC board is also transferred onto thechamber guide rails by the push mechanism.

The push mechanism employs first and second catch actuators that lowerand raise first and second catch fingers. The first and second catchfingers extend into the travel area of the PC boards and, in the loweredposition, are able to abuttably engage the PC boards and move them toany desired location along the conveyor or chamber guide rails. Thecatch fingers are raised when it is desired that the push mechanism passunhindered above the travel area of the PC boards. First and secondcatch sensors located on the push mechanism, together with similarsensors located on the linear drive assembly, provide infrared detectionso that the push mechanism may locate the PC boards and also properlyspace the PC boards upon the chamber guide rails for a uniform plasmareaction.

After multiple PC boards have been loaded onto the chamber guide rails,the reaction chamber is lowered upon the chamber base, whereon it isvacuum-tightly fittable, and plasma treatment is initiated usingconventional plasma generating elements. When treatment is complete, thereaction chamber is raised, and an output carrier is moved intojuxtaposition with an unload end of the chamber guide rails and the pushmechanism is caused to unload the PC boards in an analogous fashion tothe loading process.

A DC bias circuit can be included in the plasma treatment system toincrease the directionality of plasma flow and the energy level of theions and electrons in the plasma. The higher energy level also increasesthe ionization rate, thus increasing the number of ions and electrons.The increased energy level and increased ionization rate both act toproduce a higher etching rate and thus a shorter processing time. Theincreased bias also results in a more directional flow of ions onto theparts, resulting in a more anisotropic etching which is required whenetching vias and holes.

An alternative embodiment incorporates a multi-level arrangement toprovide that two or more levels of PC boards may be simultaneouslytreated by plasma reaction. In the alternative embodiment, the PC boardsare moved by a push mechanism similar to that employed in the singlelevel embodiment, but having additional catch fingers capable of beingpositioned at heights as correspond to the distance between an upper andlower pair of chamber guide rails arranged in bi-level array upon thechamber base. A first PC board is initially transferred by the pushmechanism from a stationary conveyor and onto the upper level of aninput carrier also having a bi-level array of input guide railsspaceably distanced identically to the chamber guide rails. A firstvertical position actuator raises the input carrier to bring the lowerlevel of the input carrier into alignment with the level of thestationary conveyor so that a second PC board may then be moved onto theinput carrier by the push mechanism.

The input carrier, carrying the two PC boards, is moved by a firsthorizontal position actuator to be near the chamber guide rails. Thepush mechanism then simultaneously transfers both PC boards onto theupper and lower chamber guide rails. The input carrier then moves backto be adjacent to the stationary conveyor and two additional PC boardsare reloaded as before. The additional PC boards are also transferredonto the chamber guide rails by the push mechanism, and the reactionchamber is lowered and the plasma process is begun as for thesingle-level embodiment. An output carrier identical to the inputcarrier is employed to remove the PC boards after treatment is complete.As in the first embodiment, a DC bias circuit can be included in theplasma treatment system to increase the directionality of plasma flow.When this DC bias is applied to vertical electrodes, a horizontal flowis established that improves penetration in the clearance spaces betweenparts which have been placed in multilevel arrays. This improvedpenetration allows closer spacing of layers, while still maintaininggood uniformity of treatment. Thus, throughput of parts can beincreased.

A third preferred embodiment is a plasma treatment system for treatingparts, which includes a reaction chamber, a device for supporting anumber of parts in a multilevel array and a mechanism for generating agas plasma and inducing a plasma reaction with the parts. The gas plasmamechanism including devices for applying Radio Frequency (RF) power andDC bias power to the gas plasma. This is done by providing one or moreelectrodes through which RF is used to excite the gas to a plasma state,and the DC bias is also applied to one or more elecrodes. This DC biasis used to direct the flow of the plasma, increase the ionic energy, andincrease the ionization rate. By using vertically oriented electrodes,the plasma can be made to flow horizontally between the layers of amultilevel array that holds parts that are to be treated. The applied DCbias causes a more defined directionality of flow, which allows betterpenetration of the plasma to the multilevel array, and creates moreuniformity of treatment. This improved penetration also allows closerspacing of parts and levels in a carrier, so that a carrier may havenumerous levels configured into a “cassette” or “magazine”. Use ofmagazines which carry a large number of parts allow increased throughputof parts, in either in-line, batch-processing or systems which userobotics.

An advantage of the present invention is that a plurality of parts maybe subjected to plasma treatment simultaneously in an in-line fashion,thereby speeding up processing time.

Another advantage of the invention is that none of the moving parts ofthe system are subjected to degradation from plasma reaction.

A further advantage is that the system is entirely automated, therebyproviding hands-free operation.

Yet another advantage of the invention is that parts may be loadedwithin the reaction chamber on multiple levels, thereby multiplicativelyincreasing the throughput of parts.

An additional advantage of the invention is that vertically orientedelectrodes permit better flow of the plasma over parts which arehorizontally placed, and thus more uniformity of treatment of the partsis achieved.

Another advantage of the present invention is that by using an increasedDC bias, there is better penetration of the plasma between parts inmultilevel arrays.

Yet another advantage of the present invention is that improvedpenetration allows closer spacing of levels of parts in a multilevelarray, thus allowing more levels to be placed in a given vertical space.

A still further advantage of the present invention is that by using anincreased DC bias, higher energy ions and electrons are produced, andionization rates are increased, both of which act to increase etching orcleaning rates.

A yet further advantage of the present invention is that throughputcapabilities of the treatment system is increased, and processing timeis reduced for systems which use in-line processing, for those which usebatch-processing and for those which use robotics to handle materials.

These and other objects and advantages of the present invention willbecome clear to those skilled in the art in view of the description ofthe best presently known mode of carrying out the invention as describedherein and as illustrated in the several figures of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing the single-level embodiment of thepresent invention (for clarity, in the drawing figures the PC boards areshown as not being hidden by the guide rails);

FIG. 2 is a top plan view of the embodiment of FIG. 1;

FIGS. 3a-c are explanatory partial front views of the embodiment of FIG.1 showing processing of the PC boards;

FIG. 4 is a partial front view of the embodiment of FIG. 1 showing thepush mechanism of the single-level embodiment in close-up detail;

FIG. 5 is an end view of the push mechanism of the single-levelembodiment;

FIG. 6 is a front view showing the multi-level embodiment of the presentinvention;

FIG. 7 is a top plan view of the embodiment of FIG. 6;

FIG. 8 is a partial front view of the embodiment of FIG. 6 showing thepush mechanism of the multi-level embodiment in close-up detail;

FIGS. 9a-d are explanatory partial front views of the embodiment of FIG.6 showing processing of the PC boards;

FIG. 10 is an end view of the push mechanism and input carrier of themulti-level embodiment;

FIG. 11 is a top plan view of a multilevel embodiment which has verticalelectrodes;

FIG. 12 is an electrical schematic of the circuits which apply RF and DCpower to the plasma chamber of the present invention;

FIG. 13 is a front view of reaction chamber of the batch-processingembodiment of present invention with the front door removed; and

FIG. 14 is a top plan view of the batch-processing embodiment of thepresent invention with the top enclosure surface and the ground shelfremoved.

BEST MODE FOR CARRYING OUT THE INVENTION

The preferred embodiment of the presenet invention is a plasma treatmentsystem for increased throughput plasma treatment and cleaning of any ofa variety of parts and components. The present invention can be used toincrease efficiency and cut processing time in a number of differentconfigurations, including in-line processing, batch processing, andprocessing which use robotics for material handling. The plasmatreatment system of the preferred embodiment, although generallyapplicable to any substrate susceptible of plasma reaction, is directedtoward use within the electronics industry, and more particularly towardassembly and packaging applications associated therewith, and is setforth in FIG. 1, where it is designated therein by the general referencecharacter 10.

Referring to the front view of FIG. 1 of the drawings, the plasmatreatment system 10 is shown to include the primary components of aconveyor input assembly 12, a reaction chamber 14 and chamber base 16, achamber lifting assembly 18, a push mechanism 20 and associated lineardrive assembly 22, an output assembly 24, an electronic control system26, and a vacuum and plasma generating system 27. In the particularpreferred embodiment 10 shown, printed circuit boards (PC boards) 28 arethe electronic parts that are to undergo plasma reaction treatment,although it is to be understood that many other varieties of substrateobjects may be substituted.

Referring now to both FIG. 1 and to the top plan view of FIG. 2, theconveyor input assembly 12 utilizes a number of different positioningand movement elements to assist in the transport of the PC boards 28 tothe reaction chamber 14. Among these elements are a conveyor 30 and aconveyor position actuator 32, upon which the conveyor 30 is mounted.The conveyor 30 receives a PC board 28, possibly from a previousconveyor (not shown), as in a typical inline assembly operation, or froma “cassette”(also not shown) which may contain a number of PC boards 28,and then moves the PC board 28 horizontally in conveyor-belt fashion toa position farther along the conveyor 30 and closer to the reactionchamber 14. The conveyor 30 may be of a conventional belt, wire orroller type. A pair of conveyor guide rails 34 provide alignment for thePC boards 28 during the conveyance. In addition, the conveyor guiderails 34 are adjustable so that PC boards 28 of different widths may betransported.

Positional information as to the location of the PC board 28 upon theconveyor 30 is provided by first and second conveyor sensors 36 and 38.The first and second conveyor sensors (36 and 38) are of the infraredvariety and are located at each end of the conveyor 30. Thus, theinitial appearance of a PC board 28 upon the conveyor 30 is detected bythe first conveyor sensor 36, which signals an activation of theconveyor 30 to begin carrying the PC board 28 forward until the PC board28 is detected by the second conveyor sensor 38. Upon this latterdetection, movement along the conveyor 30 ceases and the PC board 28waits to be transferred within the reaction chamber 14. Still referringto FIGS. 1 and 2, the chamber lifting assembly 18 includes two chamberlift actuators 40 and four chamber guide rods 42, the latter beingassociated with a number of pillow blocks 44. The chamber lift actuators40, which are of a conventional pneumatic nature and are commerciallyavailable, are supportingly located beneath a first side wall 46 and asecond side wall 48 of the generally box-shaped and open-bottomedreaction chamber 14. The chamber lifting assembly 18 provides for avertical lifting of the entire reaction chamber 14 off of and above thechamber base 16 in order that the PC board 28 may be transferred withinthe reaction chamber 14. The chamber guide rods 42, which aresymmetrically located near the four corners of the reaction chamber 14,stabilize the reaction chamber 14 as it is being lifted. The chamberguide rods 42 are snugly slidable within the pillow blocks 44 andthereby maintain a strict vertical movement of the reaction chamber 14.It is apparent that chamber lift actuators 40 of a variety other thanpneumatic in operation might be employed and, moreover, that a varietyof lifting or displacement mechanisms might be suitably employed to liftthe reaction chamber 14. It is therefore not intended that the invention10 be limited to the particular lifting assembly 18 shown.

Referring now to FIG. 3a, upon activation of the chamber lift actuators40, the reaction chamber 14 is lifted to a height such that the conveyor30 has suitable clearance for horizontal movement beneath the reactionchamber 14. This horizontal movement is provided by the conveyorposition actuator 32. The conveyor position actuator 32 is acommercially available component of the so-called “rodless air cylinder”variety and travels along an associated position actuator guide 50. Theposition actuator guide 50 is oriented in the direction of the reactionchamber 14 and is of a length such that when movement of the conveyorposition actuator 32 has stopped at the end thereof, the conveyor 30(and thus the PC board 28 carried thereon) is caused to be extended intothe area of the chamber base 16. A pair of chamber guide rails 52 areadjustable similarly to the conveyor guide rails 34 and are set to thesame dimensions and height as the conveyor guide rails 34. Thus, oncethe conveyor 30 has been transported the length of the position actuatorguide 50, the conveyor guide rails 34 are caused to be juxtaposedlyaligned with the chamber guide rails 52. Upon such juxtaposition, thepush mechanism 20 is employed to move the PC board 28 onto a load end 54of the chamber guide rails 52 and then farther along the chamber guiderails 52 to a predetermined position thereon. (The two ends of thechamber guide rails 52 have been denoted within the drawings as a loadend 54 and an unload end 56, in accordance with the direction of flow ofparts through the plasma treatment system.)

It is apparent that the conveyor guide rails 34 and chamber guide rails52 might take many forms. While in the preferred embodiment the guiderails (34 and 52) have an appearance not unlike the rails of a railroadtrack (albeit a miniature version thereof) such is not necessary.Indeed, it is possible to employ but a single guide rail upon whichparts may be transported when held by a suitable holder adapted totravel upon such a solitary guide rail. The chamber guide rails 52,especially, might also be more in the form of a shelf. Such a shelfcould be either heated (e.g., with a heating element on the underside)or cooled (e.g., where the shelf is hollow, or has cavities, and achilled liquid is circulated therethrough) as desired to enhanceprocessing.

The versatility and capabilities of the push mechanism 20 (and theassociated linear drive assembly 22) are of key importance to theadvantages offered by the plasma treatment system 10 and the efficiencyobtained thereby. As shown in the close-up view of FIG. 4, and in theend view of FIG. 5, the push mechanism 20 includes a vertically disposeddrive attachment portion 58, a horizontally disposed, T-shaped armmember 60, which is joined to the top of the drive attachment portion 58at the base of the “T”, and first and second catch assemblies 62 and 64.The first and second catch assemblies (62 and 64) are located at eachend of the cross portion of the “T” of the arm member 60 and includefirst and second catch actuators 66 and 68, respectively. The first andsecond catch actuators (66 and 68) act to lower and raise attached firstand second catch fingers 70 and 72, which are horizontally disposedmembers having lengths that permit extension over the travel area of thePC board 28. The catch actuators (66 and 68) are commercially availablepneumatic devices having air cylinders and spring returns. First andsecond catch blocks 74 and 76, present at the ends of the first andsecond catch fingers (70 and 72), respectively, and depending therefrom,permit abuttable engagement of the PC board 28 when the catch fingers(70 or 72) are in a lowered position. A first and second catch sensor 75and 77, which are of the infrared variety, are also located at the endsof the first and second catch fingers (70 or 72), respectively, andprovide for detection of the PC boards 28. It will be apparent that avariety of configurations for the dispositions and shapes of thecomponents as comprise the push mechanism 20 may be employed to achievethe “catching” and “pushing” ability of the push mechanism 20 (theoperation of which will be described in more detail later herein). Forexample, the catch actuators (66 and 68) might be relocated from the armmember 60 to the ends of the catch fingers (70 and 72), with the catchfingers (70 and 72) then attached directly to the arm member 60 and thecatch blocks (74 and 76) attached directly to the catch actuators (66and 68), such that only the catch blocks (74 and 76) are raised andlowered, among many other possible configurations. The push mechanism 20might also take the form of a “pull” “mechanism” where parts areprocessed which accommodate this or are held in a holder adapted topermit such. Therefore, the description of the push mechanism 20 asapplies to the invention 10 is not intended to be limited to just theparticular arrangement as has been set forth.

Continuing to refer to FIG. 4, the linear drive assembly 22 includes theprimary components of an A.C. motor 78 and associated drive gear 80, adrive rack 82, and a guide rack 84 and guide bearing 86. The lineardrive assembly 22 provides for linear travel of the push mechanism 20along most of the length of the plasma treatment system 10 in a relationparallel to the first conveyor and chamber guide rails (34 and 52).Travel impetus and “pushing” ability for the push mechanism 20 isaccorded by the A.C. motor 78, which has a variable speed capability andis reversible. The A.C. motor 78 is engageably mounted to the drive rack82 via the drive gear 80, while the drive attachment portion 58 of thepush mechanism is slidably mounted on the guide rack 84 via the guidebearing 86, which maintains the drive attachment portion 58 in avertical orientation during travel. It will be understood that theprecise nature of the linear drive assembly 22 is not of criticalimportance to the invention 10 herein and that drives of other designs,and which utilize various other components, may perform a substantiallysimilar movement function (e.g., a ball screw drive and/or a belt andpulley arrangement, etc.). The linear drive assembly 22 is also providedwith a plurality of drive sensors 88 (see FIG. 2) which provideinformation as to the positional status of the push mechanism 20 at anygiven moment as the push mechanism 20 moves along the lengths of thedrive and guide racks (82 and 84). Referring back now to FIGS. 2 and 3a,as noted previously, the lengths of the first and second catch fingers(70 and 72) are such as to extend over the travel area of the PC board28. The first catch sensor 75 functions to locate the PC board 28. Oncethe PC board 28 has been located, the first catch actuator 66 causes thefirst catch block 74 to be downwardly extended to a position behind thePC board 28 and to be in abuttable proximity thereto. Upon activation ofthe linear drive assembly 22, the push mechanism 20, by way of theabutting first catch block 74, moves (“pushes”) the PC board 28 to thedesired location along the chamber guide rails 52 and to a predeterminedlocation fully within the perimeter of the chamber base 16.

Importantly, the push mechanism 20, in conjunction with chamber guiderails 52 of appropriate length, provides that a multiplicity of PCboards 28 (or other parts), depending on their size, may be loaded intothe reaction chamber 14 for simultaneous plasma treatment. The pushmechanism 20 and associated infrared catch sensors (75, 77, and 88)provide that the parts are correctly spaced (via programmed instructionsthrough the electronic control system 26; see below) for a uniformplasma treatment. Thus, and referring now to FIGS. 3 and 6, after havingpositioned the first PC board 28 near the unload end 56 of the chamberguide rails 52, a second PC board 28′ may be transferred onto thechamber guide rails 52 to be located spaceably near the first PC board28 according to the sequence of operations set forth above (with anadditional step being that after the first PC board 28 has been loaded,the first catch finger and block (70 and 74) are retracted by the firstcatch actuator 66 so that the push mechanism 20 may then have sufficientclearance to pass back over the trailing second PC board 28′ in orderthat the second PC board 28′ may then be “caught” and moved forward insimilar fashion to the first PC board 28). This ability to treat byplasma teaction, in an in-line fashion, multiple PC boards 28 (or otherparts) at once, while simultaneously providing that no moving componentsof the plasma treatment system 10 are present within the reactionchamber 14 during the treatment, offers a distinct and great advantageover any prior art known to the inventors.

As is shown in FIG. 3b, after the last PC board 28′ has been loaded, thefirst catch finger 70 is raised and the push mechanism 20 is moved bythe linear drive assembly 22 to a location outside of the perimeter ofthe chamber base 16. At the same time, the conveyor position actuator 32moves the conveyor 30 back out of the reaction chamber 14 area as well.The reaction chamber 14 is then lowered by the chamber lift actuators 40onto the chamber base 16, whereon the reaction chamber 14 isvacuum-tightly fittable, and the plasma process is initiated. Referringagain to FIG. 2, there is shown a vacuum and plasma generating system 27having a number of elements of generally conventional nature. A vacuumport 90, to which is connected a vacuum pump (not shown), provides thatthe reaction chamber 14 may be evacuated to a predetermined level, whichis generally in the so-called “soft vacuum” region of 0.1-1.0 mm Hg. Agas distribution manifold 92 allows for the continuous introduction ofprocess gas (e.g., oxygen and argon) within the reaction chamber 14.Flexible Teflon® tubing (not shown) provides that the gas manifold 92may be raised in conjunction with the reaction chamber 14. A plasma isgenerated within the evacuated reaction chamber 14 with a radiofrequency generator 94, there being provided for this purpose four radiofrequency feedthroughes 96 which are located in the chamber base 16. Anelectrode 98 for the application of high voltage, to which the chamberguide rails 52 are clamped with guide rail clamps 100 (see FIG. 1) andconveniently supported thereby, provides that plasma reaction may thenoccur at the surface of the PC boards 28. It will be apparent to thosewith ordinary skill in the art that other electrical and radio frequencyconfigurations for the chamber guide rails 52 might be employed. Thus,the chamber guide rails 52 might be radio frequency powered, orgrounded, or electrically “floating” (isolated), or some combination ofthe foregoing. Additionally, a DC bias circuit can be included in theplasma treatment system to increase the directionality of plasma flowand the energy level of the ions and electrons in the plasma. The higherenergy level also increases the ionization rate, thus increasing thenumber of ions and electrons. The increased energy level and increasedionization rate both act to produce a higher etching rate and thus ashorter processing time. The increased bias also results in a moredirectional flow of ions onto the parts, resulting in a more anisotropicetching which is required when etching holes and vias. Anisotropicetching provides straight wall etching which decreases undercutting.This DC bias circuit is discussed in more detail below (see FIG. 12).

To reiterate, since the plasma treatment system 10 incorporates a methodof transfer that provides that no moving parts are located within thereaction chamber is 14 during plasma treatment, no moving parts aredegraded, and no contaminants (from machine oils or lubricants) areintroduced onto the treated PC boards 28. When the plasma treatment iscompleted, nitrogen is introduced into the reaction chamber 14 to bringthe pressure of the reaction chamber 14 up to atmospheric level, and thereaction chamber 14 is again lifted up and out of the way via thechamber lift actuators 40. Referring again to FIGS. 1 and 2, and also toFIG. 3c, the output assembly 24 is comprised of components essentialidentical to the conveyor input assembly 12, but without a conveyor-belttype capability, and provides an analogously reverse function thereto.Thus, a position actuator 102 moves an output carrier 104, which ismounted thereon, into close proximity to the unload and 56 of thechamber guide rails 52. The second catch sensor 77 present on the pushmechanism 20 locates the first PC board 28, whereupon the second catchactuator 68 lowers the second catch finger and block (72 and 76) inorder that the first PC board 28 may be pushed along the chamber guiderails 52 and unloaded onto an adjustable pair of output carrier guiderails 106. The output carrier 104 is then moved by the position actuator102 (along an associated position actuator guide 108 as before) awayfrom the reaction chamber 14 so that transfer of the PC board 28 (by thepush mechanism 20) to the next station may occur. The remaining PCboard(s) 28′ is moved onto the output carrier 104 by the push mechanism20 in similar fashion. Prior to the re-lowering of the reaction chamber14, and while the unloading of the treated PC boards 28 is occurring,untreated PC boards 28 are again loaded into the reaction chamber 14 forplasma treatment following the steps outlined above. In addition to theaforementioned advantages, the plasma treatment system 10 of the presentinvention provides that parts may be treated by plasma reaction withoutever having to remove them from the assembly line, thereby reducingoverall process time.

As shown in FIG. 1, the flowthrough of parts through the plasmatreatment system 10 is controlled by the electronic control system 26,which controls the conveyor input and output assemblies (12 and 24), thepush mechanism 20 and associated linear drive assembly 22, and thechamber lifting assembly 18. The electronic control system 26incorporates a microprocessor (not shown) and employs standard SMEMAcommunication.

Shown in the front view of FIG. 6 is an alternative embodiment of thepresent invention, in which there is provided a means by which an evengreater number of PC boards or other parts may be subjected tosimultaneous plasma treatment. The alternative embodiment employscomponents very similar to the aforementioned embodiment, but somodified as to achieve a multi-level loading of PC boards within thereaction chamber and thereby making possible a multiplicativelyincreased throughput of PC boards or other parts. The alternativeembodiment is designated as 410 in the drawings, and to the extent thoseelements of the alternative embodiment 410 are substantially identical(or closely correlate) to those previously appearing in the single-levelembodiment 10, they will be referred to by a reference numberincorporating the original reference number prefaced with the digit “4”.New elements which appear will be numbered in continuous fashion frompreviously numbered elements of the single-level embodiment 10,beginning with the number “110”. Referring now to both FIG. 6 and thetop plan view of FIG. 7, a stationary conveyor 430 is essentiallyidentical to the conveyor 30 of the single-level embodiment 10, having apair of adjustable conveyor guide rails 434 for receiving a PC board 28from, e.g., a previous conveyor (not shown), but does not move upon aconveyor position actuator (32). An input carrier 110 does move along afirst horizontal position actuator 432 in similar fashion to theprevious conveyor and output carrier (30 and 104) and, in addition, isprovided with a first vertical position actuator 112 and two pairs ofadjustable upper and lower input guide rails 114 and 116 in arrayed inbi-level fashion. The first vertical position actuator 112 acts to raiseand lower the input carrier 110 such that when the input carrier 110 isin the lowered position the upper input guide rails 114 thereon are inco-planar and co-linear alignment with the conveyor guide rails 434.Alternatively, when the input carrier 110 is in the raised position, thelower input guide rails 116 are made to be in alignment with theconveyor guide rails 434. The vertical position actuator 112 is acommercially available pneumatic device, as before.

A reaction chamber 414 is vertically raiseable as before, and isassociated with all of the relevant plasma-generating elements of thesingle-level embodiment 10 (including a vacuum port 490, a gasdistribution manifold 492, a radio frequency generator 494, and fourradio frequency feedthroughes 496), but now contains therein two pairsof adjustable upper and lower chamber guide rails 118 and 452 mounted inbi-level array upon upper and lower electrodes 120 and 498. The upperand lower chamber guide rails (118 and 452) are spaceably separated by adistance identical to the distance between the upper and lower inputguide rails (114 and 116) of the input carrier 110. An output carrier122 is identical to the input carrier 110.

As shown in FIG. 8, the multi-level embodiment 410 incorporates a lineardrive assembly 422 as before, but a push mechanism 420 now includesfirst and second catch assemblies 462 and 464 having first and secondcatch actuators 466 and 468 which are attached not only to first andsecond lower catch fingers 470 and 472 (not shown) but to first andsecond upper catch fingers 124 and 126 (see FIG. 7) as well. The lengthsof the catch fingers (470, 472, 124, and 126) are again such as toextend over the travel areas of the PC boards 28. In operation, andreferring now to FIGS. 6 and 9a, and also to the end view of FIG. 10, afirst catch sensor 475 present on the push mechanism 420 locates the PCboard 28 as before. The first catch actuator 466 then lowers the firstlower catch finger 470 such that a first catch block 474 may abut andpush the PC board 28 when the linear drive assembly 422 is activated.The push mechanism 420 moves the PC board 28 onto the upper input guiderails 114 of the input carrier 110. The first vertical position actuator112 then raises the input carrier 110 so that a second PC board 28′ maybe pushed onto the lower input guide rails 116. During the transfer, theupper catch fingers (124 and 126) are maintained in a raised state sothat catch blocks 128 and 130 thereon do not to interfere with the firstPC board 28 present on the upper guide rails 114. In addition, it willbe noted that the two levels of the input carrier 110 are spaceably heldapart by spacer members 132 which are located at one side of the inputcarrier 110 only, whereby the spacer members 132 do not interfere withthe travel of the lower catch fingers (470 and 472) between the twolevels. (The upper and lower chamber guide rails (118 and 452) aresimilarly arranged.)

As shown in FIG. 9b, the reaction chamber 414 is lifted out of the wayas before, and with the two PC boards 28 and 28′ riding upon the inputcarrier 110, the input carrier 110 is moved by the first horizontalposition actuator 432 to be in a neighboring position to the upper andlower chamber guide rails (118 and 452). The push mechanism 420 thensimultaneously moves the two PC boards (28 and 28′) onto the chamberguide rails (118 and 452) to a predetermined position thereon. The inputcarrier 110 is lowered and relocated to be adjacent to the stationaryconveyor 430 so that two additional PC boards 28″ and 28″′ may betransported from the stationary conveyor 430 and onto the upper andlower chamber guide rails (118 and 452) as before.

Referring to FIG. 9c, after the second pair of PC boards (28″ and 28″′)have been loaded, the reaction chamber 414 is lowered and the plasmatreatment process is begun. Finally, as shown in FIG. 9d, aftertreatment and raising of the reaction chamber 414, the PC boards 28 areunloaded from the reaction chamber 414 by the push mechanism onto theoutput carrier 122 in reverse fashion to that previously described forthe loading process (the second upper and lower catch fingers (472 and126) being employed in the unloading process to achieve maximum pushdistance). Additional PC boards 28 will have already been reloaded ontothe input carrier 110 to provide that throughput of the PC boards 28through the system 410 is as rapid as possible. Thus, the input carrier110 acts as a “buffer.”

The second level of the multi-level embodiment 410 doubles the number ofparts that may be treated at one time. It is apparent, of course, thatadditional third and fourth levels, or more, could be added to furtherincrease the throughput of parts. In addition, the different levels neednot be in arranged in stacked alignment as shown, but rather might bestaggered to achieve a close packing to the limit permitted by the needfor a uniform plasma reaction. (A third position actuator that providesmovement in a direction perpendicular to the horizontal positionactuator 432 could be incorporated into the input and output carriers(110 and 122) in order to facilitate this. Similarly, the push mechanism420 could incorporate additional actuators to provide for a retractablehorizontal extension of the catch fingers (470 and 472) over more thanone travel area. Such a system could be adapted for the single-levelembodiment 10, as well.)

As further levels are added, the flow of plasma between parts may becomeimpeded. If electrodes are configured horizontally, movement of chargedions and active species will be vertical. Parts that are placed onhorizontal supports or shelves in the treatment chamber tend to blockplasma flow to surfaces of parts placed on intermediate levels. The endportions of parts, being more directly in the vertical flow path of theplasma, can become over-treated to the point of causing damage, whilethe middle portions, to which plasma flow has less easy access, can beunder-treated. This results in undesirable non-uniformity.

It is possible to improve uniformity of treatment by stacking parts onedge vertically, to better correspond with the plasma flow direction.However, this has disadvantages because gravity cannot be as easily usedto align parts. Parts stacked on their edges may require carriers withedge-width slots. Placement of parts in these carriers becomes moredifficult, more handling may be necessary, and processing time isgenerally increased.

The present invention addresses these problems by providing a set ofelectrodes which are vertically oriented. This produces a horizontalplasma flow that is more compatible with multi-level arrangements ofparts which are horizontally oriented.

Secondly, in addition to Radio Frequency (RF) excitation power, anincreased DC bias is applied to the electrodes. Adding DC bias to thesystem increases the electric field strength, which in turn increasesthe energy of the ions in the plasma. This encourages a more defineddirectional flow of the ions from electrode to electrode, thus improvingpenetration of the plasma into the clearances between the stacked layersof parts. Improved penetration allows better uniformity of treatment ofthe parts, as the plasma is better able to contact the working surface.This improved directionality of flow also allows closer spacing oflayers while maintaining good uniformity of treatment. More layers andthus more parts can be simultaneously processed in each treatment cycle,for greater manufacturing throughput.

FIG. 11 illustrates a top plan view of a multilevel in-line plasmatreatment system 410, having vertical electrodes 598. Reacfion chamber414 contains a series of levels, each of which have associated guiderails, as in the previous description. The upper chamber guide rails 118are shown which are ready to receive a part or substrate (not shown) ina horizontal orientation. Vertical electrodes 598 extend from the baseto above the upper-most level and excite the plasma which flows in adirectional manner from electrode 598 to electrode 598 as indicated byarrows 550. It should be understood that there may be considerablevariation in the location and positioning of the DC bias application.For example, the DC bias need not be applied to the same set ofelectrodes as the RF power. There could thus be horizontal electrodeswhich apply the RF power and vertical electrodes which use a DC biasvoltage to direct the plasma flow across the horizontal parts.

FIG. 12 illustrates the electrical circuit 500 used to power the plasmatreatment system 510. The two electrodes 598 are contained within thereaction chamber 414 and include a powered shelf 510 and a ground shelf520. A Radio Frequency power supply 504 supplies RF power to the poweredshelf 510 through electrical feed-throughs (see FIG. 13). RF power flowsgenerally from the powered shelf 510 to the ground shelf 520, and the RFpower is primarily used to excite the gas to a plasma state.

Superimposed on the RF power is a DC potential. AC power is supplied toan AC input of a DC power supply 502, which supplies DC in aconventional manner. DC power is applied to the electrodes 598. The gasin the chamber has a certain electrical resistance and when a DC voltageis applied, a DC bias is created. In the preferred embodiment, thenegative output of the DC supply will be connected to the RF powershelf. The positive output of the DC supply is applied to the groundshelf which shifts the RF signal by −150 volts with respect to ground. Afilter 530 acts in a conventional manner as a band-reject filter toprevent RF power from flowing into the DC supply 502. It will beunderstood that the amount and polarity of the DC bias is subject tovariation, depending on a number of factors such as the plasma speciesinvolved, the spacing of the levels, etc. and the present invention isnot limited to the values disclosed here. Also, there may beconsiderable variation in the location and positioning of the DC biasapplication. For example, the DC bias need not be applied to the sameset of electrodes as the RF power. There could thus be horizontalelectrodes which apply the RF power and vertical electrodes which use aDC bias voltage to direct the plasma flow across the horizontal parts.Both DC and Radio Frequency excitation of plasma as used independentlyare well known in the art, but the inventors of the present inventionare unaware of any other system which uses both DC and Radio Frequencypower concurrently for plasma treatment.

As stated above, the improved directionality of flow provided by thepresent invention allows closer vertical placement of parts in layerswhich can be simultaneously treated. This opens the way for use ofprefigured containers with many layers which can be loaded either whileinside the reaction chamber, as in the previous embodiments, or loadedprevious to placement of the containers in the chamber. These containersare known as “cassettes” or “magazines”, and can be used in eitherin-line processing, batch-processing, or integrated into systems whichuse robotics to handle materials.

If used in an in-line manner, the magazines can be loaded by anautomated mechanism similar to the input carrier 110 previouslydescribed (see FIG. 9). The loaded magazines can then be sent on aconveyer mechanism, to be placed in the reaction chamber, and eventuallyextracted and conveyed onward by an output carrier similar to the oneshown as 122 in FIG. 9.

If used in a batch-processing manner, the magazines can be used with avariety of reaction chamber configurations, which have been fitted withvertical electrodes and DC biasing circuitry, as previously described.FIG. 13 shows a third embodiment of a plasma treatment system 610, whichcan be used in manual batch-processing manner or used with roboticmanipulation. A plasma treatment system 610 is shown, having anenclosure 612 surrounding a reaction chamber 614. A ground shelf 520 anda powered shelf 510 are shown having attached vertical electrodes 598.Magazines 620 filled with parts to be treated are shown seated on anadjustable shelf 622. The sides (not shown) of the magazines are eitheropen or have slots fashioned to allow plasma flow to reach the parts. ADC bias applied to the powered and ground shelves serves to directplasma flow through the magazine side slots or open sides to allowuniform treatment, in the manner previously described. The DC and RFpower is input to the powered shelves by first and second sets ofelectrical feed-throughs 624, 625.

FIG. 14 illustrates a top plan view of a plasma treatment system withthe top surface of the enclosure 612 and the ground shelf 520 removed. Anumber of magazines 620 are shown which have been placed in two columnsof four magazines. Electrodes 598 are shown in two separate banks, afirst bank 626 and a second bank 628, which serve the two columns ofmagazines. Both the RF power supply 504 and the DC power supply 502 areconnected to the electrodes 598 through the feed-throughs. In this view,only the first set of feed-throughs 624 is visible. This set 624 may be(for example) connected to the first bank of electrodes 626, whichserves the first column of magazines, while the second bank 628 servesthe second column. It should be appreciated that the connection betweenthe power supplies and the electrodes could be accomplished in manydifferent ways and more or fewer banks of electrodes and/or columns ofmagazines could be used. For example, one long electrode could replacethe two shorter ones seen in the figure, resulting in a single electrodebank which services both columns of magazines. In this preferredembodiment, all powered vertical electrodes are connected to a centralhorizontal electrode.

Also shown in this view are the RF filter circuit 530 and a DC biaslevel adjustment 640. This adjustment 640 can be used to change the biaslevel to accommodate different vertical clearances between levels anddifferences in gas species.

In this embodiment, a door 632 is shown for front-loading of magazines620. Although this embodiment is adapted for manual loading ofmagazines, it is to be understood that many other variations arepossible which encompass the full spectrum of operations from strictlymanual manipulation to full automated, hands-free operation. Forexample, the enclosure could have front and rear doors which aremechanically operated, and robotics can be used for loading, placementand conveyance of the magazines. Also, as discussed previously, thepresent invention can be used in either batch-processing or in-lineprocessing configurations or any combination of the two. The presentinvention 10, 410, and 610 increases throughput and decreases processingtime for any of these variations.

In the three preferred embodiments of the plasma treatment system (10and 410, 610), the reaction chamber (14 or 414) is made of stainlesssteel with fixtures of aluminum, although other plasma-resistantmaterials, such as quartz may also be employed. In the preferredembodiments, the radio frequency feed-throughs 96 are protected with aconventional ceramic material.

In addition to the above mentioned examples, it is to be understood thatvarious other modifications and alterations with regard to the types ofmaterials used, their method ofjoining and attachnent, and the shapes,dimensions and orientations of the components as described may be madewithout departing from the invention. Accordingly, the above disclosureis not to be considered as limiting and the appended claims are tointerpreted as encompassing the true spirit and entire scope of theinvention.

INDUSTRIAL APPLICABILITY

The plasma treatment system 10 of the present invention is designed tobe used for the plasma treatment and cleaning of myriad types of partsand materials, including PC boards, wafers, lead frames, etc., and useof the system 10 is not limited to the electronics industry only, sinceplasma treatment and cleaning is equally applicable to susceptiblesubstrates in the fields of catalysts, medical devices, plastics,ceramics, machine parts, film, optics, and even sterilization, tomention but a few possibilities. Treatment of irregularly shaped partsmay be provided for by using special holders capable of traveling alongthe various guide rails that have been disclosed herein (or upon guiderails that have been suitably modified).

Use of the plasma treatment system 10 is simple. The in-line embodimentof the plasma treatment system 10 will generally be placed in an in-linefashion between other processing stations as part of an overall assemblyprocess. For example, parts may travel in assembly line fashion from acuring oven to the system 10, and from there on to a wire bondingapparatus. The parameters of the particular parts to undergo plasmatreatment are entered into the electronic control system 26 and thesystem 10 is activated to begin processing the parts.

The system 10 is completely automated, giving a hands-free operation,and provides that multiple parts may be simultaneously subjected toplasma treatment in an in-line manner. No moving parts are presentduring the plasma reaction process, giving the system 10 an increasedlife expectancy.

The plasma treatment system 610 can be used in a number of differentmainers. The magazines 620 can be loaded with parts either by hand or byautomated processes, such as the input carrier 110, or other roboticmeans. The loaded magazines 620 can then be placed in the reactionchamber 614 by manual, in-line, or robotic mechanisms. The applied DCbias power 502 which is applied to vertically oriented electrodes 598,creates horizontal flow which effectively penetrates into the clearancespaces between horizontal layers in the magazine 620, allowing moreuniform treatment of parts. In addition, etching rate is increased dueto the higher energy levels and the increased ionization rate. Thisallows more parts to be stacked closer together in a given height ofmagazine 620, and decreased processing time due to the increased etchingrate. The throughput of the plasma treatment system 610 is thus greatlyimproved, whether used in a batch-processing, in-line, or roboticsmanipulation manner.

For these reasons and numerous others as set forth previously herein, itis expected that the industrial applicability and commercial utility ofthe present invention will be extensive and long lasting.

What is claimed is:
 1. A system for treating parts by gas plasmareaction, comprising: a reaction chamber having an open bottom; achamber base to which said bottom of said reaction chamber isvacuum-tightly fittable; lifting means for achieving vertical movementof said reaction chamber relative to said chamber base; a guide meanscapable of supporting the parts during treatment and along which theparts may be moved, said guide means being located within said reactionchamber when said reaction chamber is fitted to said chamber base; inputcarrier means capable of conveying the parts to a location neighboringsaid guide means; output carrier means capable of conveying the parts toa location removed from said guide means; a vertically positionablecatch block capable of engageable abutment with the parts; a driveassembly attached to said catch block, said drive assembly capable ofmoving said catch block to transfer the parts from said input carriermeans to and along said guide means, and from said guide means to saidoutput carrier means; and gas plasma means for generating a gas plasmaand inducing a plasma reaction with the parts.
 2. The system of claim 1further including sensor means for assisting said drive assembly in themovement and positioning of the parts relative to said guide means. 3.The system of claim 2 wherein said sensor means employs infrareddetection.
 4. The system of claim 1 wherein said drive assembly includesa catch actuator for raising and lowering said catch block.
 5. Thesystem of claim 4 wherein said drive assembly further includes ahorizontally disposed catch finger having a length sufficient to extendover the travel area of the parts and to which said catch actuator andsaid catch block are attached.
 6. The system of claim 1 wherein saiddrive assembly is a linear drive assembly.
 7. The system of claim 1wherein said guide means includes a chamber shelf upon which the partsmay be slidably transported, said chamber shelf having a load end and anunload end, said chamber shelf being located upon said chamber base. 8.The system of claim 1 wherein said guide means includes a plurality ofguide rail pairs arranged in a multi-level array.
 9. The system of claim8 wherein said input carrier means and said output carrier means eachinclude a carrier having multiple levels capable of carrying the partsat different ones of said multiple levels, said multiple levelscorresponding in number to the number of levels of said multi-levelarray and being spaceably distanced from and co-planarly alignabletherewith.
 10. The system of claim 1 further comprising a horizontalposition actuator and said input carrier means and said output carriermeans each comprising a conveyor mounted upon said horizontal positionactuator for horizontal movement of said conveyor thereupon.
 11. Thesystem of claim 1 further comprising a vertical position actuator andsaid input carrier means and said output carrier means each comprising aconveyor mounted upon said vertical position actuator for verticalmovement of said conveyor thereupon.
 12. The system of claim 1 whereinsaid gas plasma means includes means for applying radio frequency powerand means for applying DC bias power.
 13. The system of claim 1 whereinsaid gas plasma means includes an electrode upon which said guide meansis mounted.
 14. The system of claim 1 wherein said gas plasma meansincludes an electrode which is vertically oriented.
 15. The system ofclaim 1 wherein said lifting means includes a chamber lift actuator. 16.The system of claim 1 wherein said lifting means includes a guide rodand a pillow block for maintenance of a generally strict verticalmovement of said guide rod.
 17. A plasma treatment system for treatingparts, comprising: a reaction chamber having an open bottom; a chamberbase to which said bottom of said reaction chamber is vacuum-tightlyfittable, said chamber bass having a perimeter; lifting means forachieving vertical movement of said reaction chamber relative to saidchamber base; a horizontally and vertically movable input carrier; ahorizontally and vertically movable output carrier; a plurality of guiderail pairs, said guide rail pairs each including two guide railsarranged in parallel to each other and being capable of supporting theparts, two of said guide rail pairs being located within a multilevelarray within said perimeter of said chamber base, two of said guide railpairs being located upon said input carrier, and two of said guide railpairs being located upon said output carrier, said guide rail pairslocated upon the input and output carriers located in a multilevel arraycapable of being moved into coplanar alignment with said guide railpairs located within said perimeter of said chamber base; catch meansfor moving and positioning the parts along said guide rail pairs; andgas plasma means for generating a gas plasma and inducing a plasmareaction with said parts.
 18. The system of claim 17 firther includingsensor means for assisting said catch means in the movement andpositioning of said parts along the guide rail pairs.
 19. The system ofclaim 17 wherein said gas plasma means includes an electrode which isvertically oriented.
 20. The system of claim 17 further comprising acatch block capable of engageably abutting the said parts when loweredand said catch means includes a catch actuator for raising and loweringsaid catch block.
 21. The system of claim 17 wherein said gas plasmameans includes means for applying radio frequency power and means forapplying DC bias power.
 22. The system of claim 17 wherein said gasplasma means includes an electrode upon which said guide rail pairslocated within said perimeter of said chamber base are mounted.
 23. Aplasma treatment system for treating parts, comprising: a reactionchamber; a pair of horizontal electrodes positioned in a substantiallyfacing and substantially parallel relationship within said reactionchamber, one of said horizontal electrodes being capable of supporting aplurality of parts arranged in a multilevel array; at least one verticalelectrode attached in electrical continuity with one of said horizontalelectrodes, each of said vertical electrodes being positioned adjacentthe multilevel array of parts; a radio frequency power supply operablyconnected to one of said pair of horizontal electrodes for generating agas plasma; and a DC bias power supply operably connected to said atleast one of said vertical electrodes, said DC bias power enhances theinteraction of the gas plasma with the parts, reduces processing timeand increases system throughput.
 24. The plasma treatment system ofclaim 23 wherein said multi-level array comprises a plurality of stackedslots in a magazine and the parts are positioned in said plurality ofslots.